fix: change the shape of BME floor terminal.

- change the shape of all BME floor terminal (normal, sink and wide) from 5x2.5 to 5x5 requested by Zzq and Lee623.
- change icons according to above changes.
- add some comment in prototype files.

assets/jsons/chris_vanilla.json5

@@ -1,4 +1,12 @@
 [
+    // One of Chris suggested more vanilla prototypes.
+    // This prototype represent a half of a normal, sink or double ribbon border,
+    // which looks like trapezoid from top to bottom.
+    // 
+    // The bottom edge of trapezoid is from origin to +X with `long_edge_length` length.
+    // The length of top edge is `short_edge_length` and it just like moving bottom edge to +Y direction.
+    // The offset between top edge and bottom edge is always 2.5.
+    // The distance from the closest point of top edge, to Y axis is `short_edge_offset`.
     {
         "identifier": "cv_trapezoid_side",
         "showcase": null,
@@ -153,6 +161,11 @@
             }
         ]
     },
+    // Same as previous one, but looks like triangle from top to bottom.
+    // 
+    // The bottom edge is from origin to +X with `edge_length` length.
+    // The tip is going to +Y.
+    // The height of this triangle is always 2.5 and the offset between tip and Y axis is `tip_offset`.
     {
         "identifier": "cv_triangle_side",
         "showcase": null,

assets/jsons/terminals.json5

@@ -1,4 +1,5 @@
 [
+    // The shared template prototype used by all floor terminals.
     {
         "identifier": "raw_floor_terminal",
         "showcase": null,
@@ -22,26 +23,30 @@
         "faces": [],
         "instances": [
             {
-                "identifier": "cv_triangle_side",
+                "identifier": "cv_trapezoid_side",
                 "skip": "False",
                 "params": {
-                    "edge_length": "2.5",
+                    "long_edge_length": "5.0",
-                    "tip_offset": "2.5",
+                    "short_edge_offset": "2.5",
+                    "short_edge_length": "2.5",
                     "height": "height",
-                    "face": "(face[0], False, False, face[3], face[4], None)",
+                    "face": "(face[0], False, False, face[3], face[4], False)",
-                    "is_sink": "is_sink"
+                    "is_sink": "is_sink",
+                    "is_ribbon": "False"
                 },
                 "transform": "ident()"
             },
             {
-                "identifier": "cv_triangle_side",
+                "identifier": "cv_trapezoid_side",
                 "skip": "False",
                 "params": {
-                    "edge_length": "2.5",
+                    "long_edge_length": "5.0",
-                    "tip_offset": "2.5",
+                    "short_edge_offset": "2.5",
+                    "short_edge_length": "2.5",
                     "height": "height",
-                    "face": "(face[0], False, False, face[3], face[5], None)",
+                    "face": "(face[0], False, False, face[3], face[5], False)",
-                    "is_sink": "is_sink"
+                    "is_sink": "is_sink",
+                    "is_ribbon": "False"
                 },
                 "transform": "move(0, 5, 0) @ scale(1, -1, 1)"
             },
@@ -61,7 +66,7 @@
                 "identifier": "floor_rectangle_bottom",
                 "skip": "not face[1]",
                 "params": {
-                    "length": "2.5",
+                    "length": "5",
                     "width": "5"
                 },
                 "transform": "move(0, 0, -height)"

assets/jsons/wide_floors.json5

@@ -166,34 +166,50 @@
                 "transform": "rot(0, 0, 90) @ scale(1, -1, 1)"
             },
             {
-                "identifier": "cv_triangle_side",
+                "identifier": "cv_trapezoid_side",
                 "skip": "False",
                 "params": {
-                    "edge_length": "2.5",
+                    "long_edge_length": "5.0",
-                    "tip_offset": "2.5",
+                    "short_edge_offset": "2.5",
+                    "short_edge_length": "2.5",
                     "height": "height",
-                    "face": "(face[0], False, False, face[3], face[4], None)",
+                    "face": "(face[0], False, False, face[3], face[4], False)",
-                    "is_sink": "True"
+                    "is_sink": "True",
+                    "is_ribbon": "False"
                 },
                 "transform": "ident()"
             },
             {
-                "identifier": "cv_triangle_side",
+                "identifier": "cv_trapezoid_side",
                 "skip": "False",
                 "params": {
-                    "edge_length": "2.5",
+                    "long_edge_length": "5.0",
-                    "tip_offset": "2.5",
+                    "short_edge_offset": "2.5",
+                    "short_edge_length": "2.5",
                     "height": "height",
-                    "face": "(face[0], False, False, face[3], face[5], None)",
+                    "face": "(face[0], False, False, face[3], face[5], False)",
-                    "is_sink": "True"
+                    "is_sink": "True",
+                    "is_ribbon": "False"
                 },
                 "transform": "move(0, width + 5, 0) @ scale(1, -1, 1)"
             },
+            {
+                "identifier": "floor_flat",
+                "skip": "False",
+                "params": {
+                    "height": "height",
+                    "length": "2.5",
+                    "width": "width",
+                    "face": "(face[0], False, False, face[3], False, False)",
+                    "is_sink": "True"
+                },
+                "transform": "move(2.5, 2.5, 0)"
+            },
             {
                 "identifier": "floor_rectangle_bottom",
                 "skip": "not face[1]",
                 "params": {
-                    "length": "2.5",
+                    "length": "5",
                     "width": "5 + width"
                 },
                 "transform": "move(0, 0, -height)"